Blanket clamp for off-set press



Nov. 6, 1962 J, GRAVES 3,062,141

BLANKET CLAMP FOR OFF-SET PRESS Filed March 1, 1961 2 Sheets-Sheet 1 FIG. I

JAMES G. GRAVES INVENTOR;

Nov. 6, 1962 J. a. GRAVES BLANKET CLAMP FOR OFF-SET PRESS 2 Sheets-Sheet 2 Filed March 1, 1961 JAMES G. GRAVES INVENTOR AGENT United States Patent Ofifice Patented Nov. 6, 1962 3,962,141 BLANKET CLAMP FQR OFF-SET PRESS James G. Graves, 115 Lake Aluma Drive, Oklahoma City, Okla. Filed Mar. 1, 1961, Ser. No. 92,646 Claims. (Cl. 191-4151) The present invention relates to lithography and more particularly to clamping means for fastening an off-set printing blanket to a lithographic cylinder.

A feature of a lithographic press cylinder is the provision of clamp means, carried by the cylinder, for holding the blanket, wrapped around the periphery of the cylinder, which receives the impression on the printing plate to be printed on the copy. The conventional clamps or holding means are provided with upstanding fixed lugs or hook members which engage holes provided in the opposing ends of the blanket. One drawback to the use of such conventional clamps resides in the tendency of the material forming the blanket to fail or yield which causes the holes in the blanket ends to pull out preventing the blanket being maintained in snug fitting relation with respect to the periphery of the cylinder. A snug fitting relation between the blanket and the cylinder is essential particularly when printing color wherein one impression must register with a previous impression.

It is, therefore, the principal object of the instant invention to provide a clamping means for securing a blanket to a lithographic press cylinder wherein the clamping means is not dependent upon that portion of the blanket forming apertures or clamp connecting holes in the ends thereof.

Another object is to provide blanket clamping means which may be used to secure a blanket to a lithographic cylinder without modification or removal of existing conventional component parts.

Still another object is to provide a device of this class which will grip opposing ends of a press cylinder blanket and securely hold the same and which permits adjusting the tension of the blanket around the cylinder.

A further object is to provide a device of this class which is easily connected with a printing cylinder blanket and wherein the blanket may be easily connected to and removed from the clamping means.

The present invention accomplishes these and other objects by providing two pairs of bar-like clamps, removably connected with opposing ends of a blanket. A plurality of draw blocks, adapted to be secured to support 'rods carried by a press cylinder, are each provided with an adjusting screw removably received by apertures in the clamps.

Other objects will be apparent from the following description when taken in conjunction with the accompanying two sheets of drawings, wherein:

FIGURE 1 is a plan view of a press cylinder with the instant device installed thereon, a portion of the blanket being broken away for clarity;

FIGURE 2 is a cross-sectional view taken substantially along the line 22 of FIG. 1;

FIGURE 3 is a View similar to FIG. 1 illustrating the position of conventional clamps rotated to an inoperative position;

FIGURE 4 is a cross-sectional view taken substantially along the line 44 of FIG. 3;

FIGURE 5 is a perspective view of part of the clamping means when installed on press cylinder clamp support rods; and

FIGURE 6 is a perspective view of the relative position of the blanket clamp bars when connected to opposing ends of a press cylinder blanket.

Like characters of reference designate like parts in those figures of the drawings in which they occur.

In the drawings:

The reference numeral 10 indicates a cylindrical off-set printing cylinder having opposing ends 12 and 14 interconnected by a wall portion 16. The wall 16 is provided with an opening 18 extending longitudinally of the cylinder between the ends 12 and 14. A shaft 20. extended through each end 12 and 14, mounts the cylinder for rotative movement. The cylinder 10 is further provided with a pair of clamp mounting rods 22 and 23 positioned in parallel spaced-apart relation longitudinally of the cylinder adjacent the opening 18. The rods 22 and 23 pivotally support a pair of longitudinally extending blanket end clamping members 24 and 25, respectively. A blanket 26 surrounds the cylinder wall 16 in close contact therewith. The length of the blanket is less than the circumference of the circle described by the cylinder wall 16 but is sufliciently long so that its opposing ends may be co-operatively connected with upstanding lug or hook members 27 formed on the clamps 24 and 25. The above parts, numbered 10 through 27, are conventional and form no part of the invention other than to set forth the conventional device on which the instant invention is designed to be used.

In carrying out the invention, the conventional blanket clamps 24 and 25 are rotated toward each other and held in this position by a clamp holder 30 comprising a U-shaped section of strap metal with each leg of the holder provided with opposing aligned set screws 32 which grip opposing sides of the clamps 24 and 25 from the underneath or inward side thereof (FIGS. 3 and 4).

A pair of clamp members 34 comprising an elongated bar 36 and one flange of an angle member 38 are flatly connected together by a plurality of screws 40 on opposin g sides of one end portion of the blanket 26. The screws 40 are positioned to co-operatively extend through a like plurality of the holes or apertures, not shown, provided in the end of the blanket. As shown by FIG. 2, the bar 'member 36 is adapted to flatly contact the longitudinal edge of the wall 16 defining one side of the opening 18 while one flange 42 of the angle member 38 is positioned toward the arc described by the cylinder wall and proiects toward the other side of the opening 18. This flange 42 is providedwith a pair of apertures 43 each having a narrow slot opening to the free edge of the flange. Another pair of clamps 44, identical to the clamps 34, including a bar member 46. an angle member 48 and a plu-l rality of clamp holding blanket gripping screws 50 is similarly connected to the other end portion of the blanket 26. The an le member 48 similarly includes a flange portion 52, which projects toward the flange 42 and is provided with a pair of spaced-apart apertures or openings 53, each having a narrow slot open to the free edge of the flange.

A pair of substantially rectangular draw blocks 56 and 57 are each provided with a U-shaped slot or recess 58 which cooperatingly receives the rod 23. A bolt or screw 69 is threadedly engaged through the ends of the draw block forming the recess 58 to maintain the draw block in position on the rod 23. A draw block screw 62 is threadedly carried by the end portion of the respective draw block opposite the recessed end. Each of the screws 62 are positioned perpendicular with respect to the longitudinal axis of the rod 23 and are provided with an enlarged flat head end 64- which is nested by the respective aperture 43. The shank of the screws 62 is flattened on opposing sides adjacent the head end to be easily inserted through the narrow slot forming a part of the respective aperture 43. As shown in FIG. 2, the draw blocks 56 and 57, in cooperation with the screws 62, hold the blanket gripping clamps 34 adjacent one longitudinal surface of the cylinder wall 16.

Similarly, a second pair of draw block clamps 66 and 67, are each provided with a recess or slot 68 which cooperatingly receives the rod 22 while screws 70 maintain these draw blocks connected with the rod 22. Other draw block screws 72 are threadedly engaged with the end portion of the draw blocks 66 and 67, opposite their connection with the rod 22, and are similarly cooperatingly received by the apertures 53 in the angle member 52.

With the clamp members 34 and 44 connected with opposing ends of the blanket 26 and connected with the respective draw blocks by the screws 62 and 72, as shown in FIG. 2, the screws 72 may be tightened which places the blanket 26 under a desired tension around the cylinder wall 16. When tightening the screws 72, the draw blocks 66 and 67 tend to rotate the head end of the screws 72 toward the adjacent surface of the blanket. To prevent this action a bar guide member 74 is placed under each end portion of the clamps 44 and extends between the rod 22 and the adjacent surface of the wall 16 defining one side of the opening 18. Each bar guide comprises a length of strap metal having an arcuately formed end portion 76 which cooperatingly grips a peripheral portion of the rod 22, while its opposite end portion extends transversely of the clamps 44 with its free end edge contacting the edge surface of the cylinder wall 16.

The blanket is removed from the cylinder by simply loosening the draw block screws 62 and 72, which releases the clamps 34 and 44. The draw blocks 657 and 66-67 remain connected with the respective rod 22 and 23. The clamps 34 and 44 may then be removed from the blanket 26 by reversing the installation as described hereinabove.

A substantially U-shaped metallic shield 80 is provided for covering the exposed surfaces of the conventional clamps 24 and 25. The shield 89 is provided with oppositely disposed inwardly directed co-operating lugs 82 and 83 which frictionally engage the respective clamps 24 and 25 to maintain the shield in place.

Obviously the invention is susceptible to some change or alteration without defeating its practicability, and I therefore do not wish to be confined to the preferred embodiment shown in the drawings and described herein, further than I am limited by the scope of the appended claims.

I claim:

1. Blanket clamping means for a lithographic press cylinder, said cylinder having a longitudinally extending opening in its wall and having a pair of parallel support rods extending between its ends spaced inwardly of the opening in said wall, including: pairs of clamp members adapted to be secured to opposing ends of a press cylinder blanket; a pair of draw blocks secured to each said rod in spaced-apart relation intermediate its ends; an adjusting screw threadedly carried by each said draw block and removably received by said pairs of clamps; and a pair of bar guides frictionally secured at one end to one said rod and extending under one said pair of clamp members in supporting relation, the other end of each said bar guide contacting the wall of said cylinder defining one side of the opening.

2. Clamping means for securing a press cylinder blanket to a lithographic press cylinder, said cylinder having a longitudinally extending opening in its wall and having a pair of parallel support rods extending between its ends spaced inwardly of the opening in said wall, including: a pair of clamp members adapted to enter said cylinder opening and be secured to opposing ends of a press cylinder blanket; a draw block secured to each said rod intermediate its ends; an adjusting screw threadedly carried by each said draw block and connected to said pairs of clamps; and a bar guide frictionally secured at one end 4 to one said rod and extending under one said pair of clamp members in supporting relation, the other end portion of said bar guide contacting the wall of said cylinder defining one side of the opening.

3. Clamping means for securing a press cylinder blanket to a lithographic press cylinder, said cylinder having a longitudinally extending opening in its wall and having a pair of parallel support rods extending between its ends spaced inwardly of the opening in said wall, including: a pair of clamp members adapted to enter said cylinder opening and be secured to opposing ends of a press cylinder blanket, said clamp members each having an apertured flanged edge projecting toward the opposite end of the blanket; a draw block secured to each said rod intermediate its ends; an adjusting screw threadedly carried by each said draw block and removably received by the aperture in the flanged edge of the respective said pairs of clamps; and a bar guide frictionally secured at one end to one said rod and extending under one said pair of clamp members in supporting relation, the other end portion of said bar guide contacting the wall of said cylinder defining one side of the opening.

4. Clamping means for securing a blanket to a lithographic press cylinder, said cylinder having a longitudinally extending rectangular opening in its wall and having a pair of support rods extending between the ends of the cylinder adjacent the opening, including: clamp means adapted to be connected to each respective end of said blanket and enter the opening in said cylinder; a plurality of draw blocks each having a bifurcated end secured to each said support rod intermediate its ends; an adjusting screw threadedly engaged with each said draw block opposite its bifurcated end and removably engaged with the respective said clamp means; and clamp guide means interposed between one said support rod and the adjacent surface of said cylinder defining one side of the opening, said clamp guide means contacting the adjacent said clamp means in supporting relation.

5. Clamping means for securing a blanket to a lithographic press cylinder, said cylinder having a longitudinally extending opening in its wall and having a pair of parallel support rods extending between the ends of the cylinder adjacent the opening, including: a pair of clamp members adapted to be secured to each end of said blanket, each said clamp member comprising an elongated bar, an angle member and a plurality of screws connecting said angle member to said bar member, one flange of said angle member having at least two apertures therein characterized by a narrow slot opening to its free edge; a plurality of draw blocks each having a bifurcated end portion receiving each respective said rod, a screw threadedly carried by the bifurcated end portion securing each said draw block to the respective said rod; an adjusting screw threadedly engaged with each said draw block opposite its bifurcated end portion, each said draw block screw having a head end portion removably received by the apertures in the flange of the respective said angle member; and bar guide members interposed adjacent one said pair of clamps between one said support rod and the adjacent surface of said cylinder wall defining one edge of the opening, each said bar guide having an arcuate end portion frictionally engaged with said support rod.

References Cited in the file of this patent UNITED STATES PATENTS 

